The present invention relates to a building security system which controls access to a building through a controlled portal, such as a locked door.
Mechanical door locking mechanisms which require a conventional key to unlock the door have been well known for many years. These mechanisms require a person to manually insert the key into the lock and turn the key to displace a bolt which, until displaced, prevents the door from being opened. This operation requires that the person locate the key, select the proper key for the particular lock, and unlock the door. The unlocking process requires one or both hands, requiring the person to set aside some or all of the items they may have been carrying. After the door is unlocked, the person must then turn the door knob to open the door. After opening the door, then any items previously set aside must be retrieved. All of these activities take time to perform, causing the person seeking access to remain outside the door for an extended period of time. The additional time spent outside the door is especially disfavorable in high-crime areas or in adverse weather conditions such as rain, snow or extreme temperatures.
Remote control or "keyless" entry systems are also well known in the art. Some systems, instead of using a conventional metal key, use hand-held electronic devices which transmit a signal to a receiver in the door which decodes the signal and, if found to be from an authorized source, unlocks the door. The hand-held transmitters may be carried in a purse or pocket like a traditional key. However, to unlock the door, hand-held transmitters still require the person seeking access to set aside some or all of the items they are carrying, locate the transmitter in, for example, their purse or pocket, and press the appropriate button on the transmitter. These hand-held transmitters therefore suffer many of the same problems as conventional keys. Unlocking doors by turning door knobs in a pre-prescribed manner also suffer many of these same problems.